1. Field of the Invention
The present invention relates to a sheet supplying device for feeding sheets which are piled in a sheet stacking portion, such as a sheet cassette, a stacker and so on, to a predetermined transport path.
2. Description of the Related Art
In order to facilitate the sheet change operation to the utmost in a conventional copying machine, it is known that the copying machine is provided with a plurality of sheet cassettes, each of which sheet cassettes respectively contains a different type of sheet in regard to its size or feeding direction, mounted in a desk located under a main body of the copying machine. The copying machine automatically selects a desired type of sheet from any one of the sheet cassettes (Japanese Laid Open Patent Publication No. 61-192637).
In the above copying machine, a sheet supplying device for feeding the sheets piled in each cassette to a sheet supply path is mounted at an upper portion of the exit side of the cassette. Although the sheet supplying device feeds the sheets one by one, it sometimes double feeds the sheets under the influence of, for example, electrostatic adhesion of the sheets.
A sheet supplying device which has means to solve such a problem has already been proposed. For example, Japanese Laid Open Patent Publication No. 53-129648 discloses a sheet supplying device which is provided with a movable pad between a contact position and a non-contact position with a roller and feeds the sheets one by one by making the coefficient of the friction of the pad smaller than that of the roller.
However, the above-mentioned conventional sheet supplying device prevents a bottommost sheet of the sheets being simultaneously fed from being supplied and a portion of the bottommost sheet still remains out of the sheet cassette. In this case, since the portion of the sheet out of the sheet cassette comes into contact with the sheet supplying device when the cassette is drawn out of the desk to resupply new sheets or make recovery from sheet jam, the sheet is sometimes damaged by the contact.
Especially, if the sheet cassette is a rotatable sheet cassette capable of feeding the sheets in lateral and longitudinal directions, the above problem is serious. In other words, if a portion of the sheet is out of the sheet cassette as mentioned above, when the rotatable sheet cassette rotates to change the sheet feeding direction, the sheet is frequently damaged. Furthermore, the damage to the sheet may make the sheet supplying operation difficult.